Greetings.
I'm brand-spankin' new to this list, so please please please excuse me if I landed this question in the wrong space/time.
I'm looking for infomation on NetApps because the company I'm working for is considering a 760 for our network. I have been told by someone who is only vaguely familiar with the NetApps that the filesystem has to be maintained in some way by running a _wac_ command, but I have been unable to find any information on such a command in a week of searching . Can anyone fill me in on the use of this _wac_ command , what it does, how often it needs to be done, and whehter or not the filer requires downtime to do it?
Thanx.
-- Eric Hunter System Administrator _______________________
eric@gigaton.com
. Can anyone fill me in on the use of this _wac_ command , what it does,
It's "wack" and it's similar to fsck for UNIX or scandisk for NT. It corrects any errors to the filesystem that may have been introduced due to unusual crashes or hardware failures.
how often it needs to be done,
Whenever the filesystem indicates corruption. This usually happens if you have a crash and/or the filer does not boot up properly and Netapp's tech support tells you to run wack. For some customers, they never have to run wack. For others, they may run into a series of bugs that require them to run it every couple of months.
Keep in mind that you won't need to run it every time your filer crashes or you have a power outage, unlike your UNIX and Windows systems, but only on rare occasions.
and whehter or not the filer requires downtime to do it?
Yes, it does. (Although that may be changing.)
Bruce
On Dec 29, Bruce Sterling Woodcock wrote:
It's "wack" and it's similar to fsck for UNIX or scandisk for NT. It corrects any errors to the filesystem that may have been introduced due to unusual crashes or hardware failures.
As Bruce said, the main difference between "wack" and fsck or scandisk is that you shouldn't need to run wack during normal operation.
In particular, unlike UNIX and NT, you don't need to run "wack" after a system panic, or when you pull the plug without shutting the system down, or after a power failure. The WAFL filesystem uses a database technique called "shadow paging with NV-RAM log replay" to maintain a fully consistent state on disk even in the face of unexpected shutdowns.
So when do you need to run wack? Suppose that you have a disk fail in RAID, and then when you try to reconstruct the data from the lost disk you discover that there is a bad sector on one of the other drives. Most of your file system data is just fine, but you've got a couple of blocks that can't be recovered. The RAID subsystem zeros both blocks, since that's the best that you can do, but now you need to run wack in order to fix things up, in case the zeroed blocks contained file system data like inodes, indirect blocks, or the free block map.
And yes, I must confess that like any computer, NetApp systems do contain the occasional bug, so WAFL has a number of checks to make sure that the on-disk data looks reasonable, and if it finds a problem it will ask you to perform a wack.
Our goal is for customers never to need to run wack, but the reality is that people sometimes do need to use it.
Dave
How long does it take to wack a fully loaded 760? By fully loaded, I mean somewhere in the 1TB range, which I think is the upper limit of the 760.
In the immortal words of E Hunter (eric@gigaton.com):
How long does it take to wack a fully loaded 760? By fully loaded, I mean somewhere in the 1TB range, which I think is the upper limit of the 760.
Six to ten hours, easily.
-n
------------------------------------------------------------memory@blank.org "Thus do `Snuff Movies' take their place with `Political-Correctness,' `Sex Addiction,' and `Postmodernism' as Godzillas of bogus moral panic, always threatening to crush the nation in their jaws, but never quite willing to take the final step of biting down. (--www.suck.com) http://www.blank.org/memory/------------------------------------------------
How long does it take to wack a fully loaded 760? By fully loaded, I mean somewhere in the 1TB range, which I think is the upper limit of the 760.
Six to ten hours, easily.
Or longer. Just make sure you use the correct version of wack when you start. Few things sucks more than to have to re-start a wack after being 4 hours into it.
Luckily it is not a frequent occurance (having to run wack).
Alex
Thanks for your help guys. Could I trouble you with a few more basic questions which I haven't as yet been able to get answered?
I'm sure you'll let me know if these are better left to the sales people, but they will help me a great deal in completing the evaluation my company wants me to write.
Basically, I understand from the literature I've read that the 760 runs a sort of modified RAID level 4. In our particular environment, recoverability is not as important as speed, we plan to set up at least three geographically dispersed sites to which service requests can be instantly routed should a server go down, so we may want to go with a different, faster, less secure RAID level. Is this an option with the 760, or does WAFL tie you to RAID 4?
>>>>>>>>>>>> Original Message <<<<<<<<<<<<<<<<<<
On 12/29/99, 10:09:11 PM, Dave Hitz hitz@netapp.com wrote regarding Re: "Wac"-ing the WAFL?:
On Dec 29, Bruce Sterling Woodcock wrote:
It's "wack" and it's similar to fsck for UNIX or scandisk for NT. It corrects any errors to the filesystem that may have been introduced due to unusual crashes or hardware failures.
As Bruce said, the main difference between "wack" and fsck or scandisk is that you shouldn't need to run wack during normal operation.
In particular, unlike UNIX and NT, you don't need to run "wack" after a system panic, or when you pull the plug without shutting the system down, or after a power failure. The WAFL filesystem uses a database technique called "shadow paging with NV-RAM log replay" to maintain a fully consistent state on disk even in the face of unexpected shutdowns.
So when do you need to run wack? Suppose that you have a disk fail in RAID, and then when you try to reconstruct the data from the lost disk you discover that there is a bad sector on one of the other drives. Most of your file system data is just fine, but you've got a couple of blocks that can't be recovered. The RAID subsystem zeros both blocks, since that's the best that you can do, but now you need to run wack in order to fix things up, in case the zeroed blocks contained file system data like inodes, indirect blocks, or the free block map.
And yes, I must confess that like any computer, NetApp systems do contain the occasional bug, so WAFL has a number of checks to make sure that the on-disk data looks reasonable, and if it finds a problem it will ask you to perform a wack.
Our goal is for customers never to need to run wack, but the reality is that people sometimes do need to use it.
Dave
can be instantly routed should a server go down, so we may want to go with a different, faster, less secure RAID level. Is this an option with the 760, or does WAFL tie you to RAID 4?
With a filer, the only option is RAID 4. Is there something in particular that would make RAID 4 a poor choice for this application?
When you say "faster, less secure", what aspect of operations are you looking at?
Your performace milage will vary, depending on what exactly you are trying to do. But the cache the filers have, along with WAFL buy you a whole lot of performance.
If you want less security and can take a hit when a disk fails, then building huge raid groups would get you where you want to be, it sounds like.
good luck.
Alex
Alexei Rodriguez wrote:
With a filer, the only option is RAID 4. Is there something in particular that would make RAID 4 a poor choice for this application?
When you say "faster, less secure", what aspect of operations are you looking at?
RAID 0. I know, I know, it sounds almost suicidal but as I said speed is more important in this instance than recovery. We'll be testing this 760 against an Auspex, which can be configured to use RAID 0, so I was wondering if the NetApps could also do this.
Its my feeling that testing this against the Auspex wouldn't be fair if NetApps is at RAID 4. We'll see if I'm wrong.
-- Eric Hunter System Administrator
_______________________
Gigaton.com, Inc. 1200 Brickell Ave. STE 680 Miami, FL 33131 Ph: +1 (305) 373 2002 Fax: +1 (305) 373 2034
_______________________
eric@gigaton.com
Alexei Rodriguez wrote:
With a filer, the only option is RAID 4. Is there something in particular that would make RAID 4 a poor choice for this application?
When you say "faster, less secure", what aspect of operations are you looking at?
RAID 0. I know, I know, it sounds almost suicidal but as I said speed is more important in this instance than recovery. We'll be testing this 760 against an Auspex, which can be configured to use RAID 0, so I was wondering if the NetApps could also do this.
Its my feeling that testing this against the Auspex wouldn't be fair if NetApps is at RAID 4. We'll see if I'm wrong.
WAFL and RAID 4 are very tightly integrated. WAFL stands for "write anywhere file layout". Whenever you update file data you must also update the inode. On conventional filesystems the location of the inode is static. This can cause write performance problems because every time you update file data, you also have to update the inode. The data block and the block containing the inode might not be be on the same stripe. In a conventional RAID system, you end up updating the stripe with the inode (data and parity) and updating the stripe with the file data (data and parity).
WAFL, on the other hand, never overwrites an inode or a data block. WAFL always replaces an old block with a new one. The old block is freed and the new block is linked into the filesystem. To accomplish this, inodes are stored in a metafile rather than in fixed locations. So what does this buy you? When writing file data you are not tied to any particular block. Any free block is suitable. This means that WAFL can use whatever free blocks happen to be currently under the disk heads. WAFL doesn't waste a lot of time bouncing the disk heads between data blocks and fixed inode blocks.
WAFL also buffers up filesystem updates so that they can be scheduled in an orderly and efficient way. RAID 4 is built into WAFL, so WAFL itself manages the parity drives. WAFL writes a burst of updates to the same stripe and only hits the parity drive once. It can also localize its updates to nearby stripes so that the parity drive heads do not move much. This makes netapp write performance blazingly fast.
Read performance cannot be enhanced by this trick because you must always move the disk heads to wherever the data you need is located. To improve read performance, recently accessed filesystem blocks are cached in RAM. Often reads can be accomplished without hitting the disks.
-- Eric Hunter System Administrator
Gigaton.com, Inc. 1200 Brickell Ave. STE 680 Miami, FL 33131 Ph: +1 (305) 373 2002 Fax: +1 (305) 373 2034
eric@gigaton.com
Steve Losen scl@virginia.edu phone: 804-924-0640
University of Virginia ITC Unix Support
On Wed, 29 Dec 1999, E Hunter wrote:
Its my feeling that testing this against the Auspex wouldn't be fair if NetApps is at RAID 4. We'll see if I'm wrong.
No, it's not fair, but I think you'll find an F760 will still beat a similarly configured Auspex. ;-) If you look at the results of the SPECsfs97 benchmarks, you'll notice that a lot of vendors "cheat" by loading up their testbeds with hundreds of drives or dozens of small filesystems or only using RAID 0+1 or only striping the outer tracks of each drive, etc. One has to wonder how much performance you lose with a real-world configuration. Netapp's benchmark results are with RAID 4, full disk usage, single filesystems. No cheating.
Check the Auspex results and take a large grain of salt with you (http://www.spec.org/osg/sfs97/results/res99q3/sfs97-19990716-00109.html). More drives, more storage adapters, more filesystems, more NVRAM, comparable CPU power == less performance, both in absolute NFS ops/sec and response times (7462 ops/sec @ 9.4 ms for a single F760 vs. 6030 @ 16.7 for a single-node Auspex).
On Thu, 30 Dec 1999, E Hunter wrote:
I'm sure you'll let me know if these are better left to the sales people, but they will help me a great deal in completing the evaluation my company wants me to write.
Sales people will tend to paint a rosier picture than reality, but the folks in here (generally being techies or engineering types) will give you the straight goods. ;-) OTOH, sales reps are good for swag. :)
[Hint: to anyone reading from netapp... need more swag! Jackets, mugs, blankets, shoulder bags, multitools, sunglasses, etc.? I've got the shirts, the swiss army knife, the baseball cap and a few other trinkets already. ;-) ]
Basically, I understand from the literature I've read that the 760 runs a sort of modified RAID level 4. In our particular environment, recoverability is not as important as speed,
The WAFL filesystem is extremely efficient when it comes to writing out entire stripes (parity and all) to disk. I doubt there would be any real performance gain assuming you switch the filer to RAID 0 (which a Netapp can't do anyway). Filers win on access times, not so much raw throughput. If you're looking for 100 MB/sec sustained writes to disk, a Netapp isn't going to cut it (yet).
What sort of application will this be for? The other thing a filer isn't fast at (and this is really the fault of NFS) is locking. We have one particular financial application that locks/unlocks rows in a database file like a sonofabitch, and it completely falls over on an NFS filesystem, so we had to go back to local storage for it. Poor software design if you ask me, but that's another story.
On Thu, 30 Dec 1999, Brian Tao wrote:
I've got the shirts, the swiss army knife, the baseball cap and a few other trinkets already. ;-)
Wow, all I've received so far is countless mugs, shirts, a Java decoder ring (a small Java machine, cute, but useless), and a completely useless cellular telephone stand (who needs to put their cell phone on a stand anyway?).
Tom
I know for a fact that NetApp-logoed golf balls exist(ed).
My favorite so far, though, is the set of "beany-baby" NetApp juggling filers. Small rectangular beanbags inprinted on the ends visages of an F7xx bezel and rear panel, respectively. These were apparently produced by NetApp Education Services and given out in classes. Unfortunately, I aquired mine third hand, and only have the one, so juggling it it not very fun... alas, maybe someday I'll track down companions for it. Don't know whether these are still "in print".
On Thu, 30 Dec 1999, Brian Tao wrote:
I've got the shirts, the swiss army knife, the baseball cap and a few other trinkets already. ;-)
Wow, all I've received so far is countless mugs, shirts, a Java decoder ring (a small Java machine, cute, but useless), and a completely useless cellular telephone stand (who needs to put their cell phone on a stand anyway?).
Tom
On Thu, 30 Dec 1999, Richard Geiger wrote:
My favorite so far, though, is the set of "beany-baby" NetApp juggling filers. Small rectangular beanbags inprinted on the ends visages of an F7xx bezel and rear panel, respectively. These were apparently produced by NetApp Education Services and given out in classes. Unfortunately, I aquired mine third hand, and only have the one, so juggling it it not very fun... alas, maybe someday I'll track down companions for it. Don't know whether these are still "in print".
I managed to convince someone to hand over those to me as well. ;) Unfortunately I'm a beginner at jugling and the fact that they are not spherical makes it difficult to juggle.
Tom
Being an amature juggler, I would *love* to get "beany-baby" filers from my sales rep... *hint* *hint*
He has been good to me though - on cold days I wear a nice leather jacket with the Network Appliance logo emblazoned on its breast! =)
-- Jeff
-- ---------------------------------------------------------------------------- Jeff Krueger E-Mail: jeff@qualcomm.com NetApp File Server Lead Phone: 858-651-6709 IT Engineering and Support Fax: 858-651-6627 QUALCOMM, Incorporated Web: www.qualcomm.com
From Richard Geiger on Thu, 30 Dec 1999 09:21:09 PST:
I know for a fact that NetApp-logoed golf balls exist(ed).
My favorite so far, though, is the set of "beany-baby" NetApp juggling filers. Small rectangular beanbags inprinted on the ends visages of an F7xx bezel and rear panel, respectively. These were apparently produced by NetApp Education Services and given out in classes. Unfortunately, I aquired mine third hand, and only have the one, so juggling it it not very fun... alas, maybe someday I'll track down companions for it. Don't know whether these are still "in print".
On Thu, 30 Dec 1999, Brian Tao wrote:
I've got the shirts, the swiss army knife, the baseball cap and a few other trinkets already. ;-)
Wow, all I've received so far is countless mugs, shirts, a Java decoder ring (a small Java machine, cute, but useless), and a completely useless cellular telephone stand (who needs to put their cell phone on a stand anyway?).
Tom
On Thu, 30 Dec 1999, Jeff Krueger wrote:
He has been good to me though - on cold days I wear a nice leather jacket with the Network Appliance logo emblazoned on its breast! =)
With the way that Qualcomm stock took off this year you should feel generous and send me the leather jacket. ;)
Tom
Wow, I'm sure we're putting our Sales Rep's kids through college, and we haven't gotten any of that stuff ;>
-Christopher CNC
On Thu, 30 Dec 1999, Brian Tao wrote:
I've got the shirts, the swiss army knife, the baseball cap and a few other trinkets already. ;-)
Wow, all I've received so far is countless mugs, shirts, a Java decoder ring (a small Java machine, cute, but useless), and a completely useless cellular telephone stand (who needs to put their cell phone on a stand anyway?).
Tom
I have seen quite a bit of these trinkets as well. I have enough golf shirts that I do not need to buy any for another couple of years. Maybe NetApp will start with the "underwear" too and then I won't need to do any shopping this year. Just trying to keep NetApp close to the heart.
-gdg
Chris Kotacka wrote:
Wow, I'm sure we're putting our Sales Rep's kids through college, and we haven't gotten any of that stuff ;>
-Christopher CNC
On Thu, 30 Dec 1999, Brian Tao wrote:
I've got the shirts, the swiss army knife, the baseball cap and a few other trinkets already. ;-)
Wow, all I've received so far is countless mugs, shirts, a Java decoder ring (a small Java machine, cute, but useless), and a completely useless cellular telephone stand (who needs to put their cell phone on a stand anyway?).
Tom
I'm holding my breath for Auspex Toilet Paper...from Netapps ;>
-Clk
I have seen quite a bit of these trinkets as well. I have enough golf shirts that I do not need to buy any for another couple of years. Maybe NetApp will start with the "underwear" too and then I won't need to do any shopping this year. Just trying to keep NetApp close to the heart.
-gdg
Chris Kotacka wrote:
Wow, I'm sure we're putting our Sales Rep's kids through college, and we haven't gotten any of that stuff ;>
-Christopher CNC
On Thu, 30 Dec 1999, Brian Tao wrote:
I've got the shirts, the swiss army knife, the baseball cap and a few other trinkets already. ;-)
Wow, all I've received so far is countless mugs, shirts, a Java decoder ring (a small Java machine, cute, but useless), and a completely useless cellular telephone stand (who needs to put their cell phone on a stand anyway?).
Tom
--
G D Geen mailto:geen@ti.com Texas Instruments Phone : (972)480.7896 System Administrator FAX : (972)480.7676
Life is what happens while you're busy making other plans. -J. Lennon
At 11:05 AM 12/30/99 -0600, tkaczma@gryf.net wrote:
On Thu, 30 Dec 1999, Brian Tao wrote:
I've got the shirts, the swiss army knife, the baseball cap and a few other trinkets already. ;-)
Wow, all I've received so far is countless mugs, shirts, a Java decoder ring (a small Java machine, cute, but useless), and a completely useless cellular telephone stand (who needs to put their cell phone on a stand anyway?).
Sniff. All I've gotten was a bottle of cheap wine with our sales rep's name on it.
-j
nice NetApp diary arrived today, must remember to fill in reminder for Y2K wakeup call later tomorrow night.
Colin Johnston SA PSINET UK
Colin Johnston wrote:
nice NetApp diary arrived today, must remember to fill in reminder for Y2K wakeup call later tomorrow night.
Gah. All I have is a netcache mug which I managed to smuggle out of their office. Mind you our account managers keep on juggling with themselves, we're on our third now, the others having moved onto netcaches from filers. BTW who else thinks it sucks that you can only have a million or so objects in a netcache. bang went another couple of sales when we discovered that...
You are just too lucky Tom. Given all the filers I have purchased at various employers, not to mention all the referrals, I have managed to obtain one (1) T-Shirt. So what's the scoop, one "T" per TB of disk? A bomber jacket for 100 filers?
Let me know when they give away a HandSpring Visor with a serial module and small app to connect to the console of my filers... :-)
~mitch
/* tkaczma@gryf.net [tkaczma@gryf.net] writes: */
On Thu, 30 Dec 1999, Jamie Lawrence wrote:
Sniff. All I've gotten was a bottle of cheap wine with our sales rep's name on it.
Oh yeah, I should add that to the list too. Got one of those. ;)
On Thu, 30 Dec 1999, Mitch Wright wrote:
You are just too lucky Tom. Given all the filers I have purchased at various employers, not to mention all the referrals, I have managed to obtain one (1) T-Shirt. So what's the scoop, one "T" per TB of disk? A bomber jacket for 100 filers?
I never said I received all these things from NetApp. I'm just a bit envious that some of the people I know and talk to obtain nice leather jackets, Columbia parkas, etc. and all I ever get is useless crap, mugs, and polo shirts.
Tom
Does anyone have a source for Netapp 9 gig drives and disk trays for a f720.
We are being told form our reseller they can only get 18gig drives now. Thats a problem for us since we just want a couple more to expand our current raidset. Not to build another raidset of larger drives. Or to format the 18gig drives to 9gig to use in the current raid set.
-Cameron Slye
For Xmas, I bought myself 45 shares of NTAP stock (@ 80). -DC
tkaczma@gryf.net wrote:
On Thu, 30 Dec 1999, Brian Tao wrote:
I've got the shirts, the swiss army knife, the baseball cap and a few other trinkets already. ;-)
Wow, all I've received so far is countless mugs, shirts, a Java decoder ring (a small Java machine, cute, but useless), and a completely useless cellular telephone stand (who needs to put their cell phone on a stand anyway?).
Tom
Wonder how many sales folk actually believe that there is a direct relationship between giveaways and meeting their end of year targets?
....or is it me thats being naive.....
-- Al
----- Original Message ----- From: tkaczma@gryf.net Cc: toasters@mathworks.com Sent: Thursday, December 30, 1999 5:05 PM Subject: Goodies (was wack)
On Thu, 30 Dec 1999, Brian Tao wrote:
I've got the shirts, the swiss army knife, the baseball cap and a few other trinkets already. ;-)
Wow, all I've received so far is countless mugs, shirts, a Java decoder ring (a small Java machine, cute, but useless), and a completely useless cellular telephone stand (who needs to put their cell phone on a stand anyway?).
Tom
[Hint: to anyone reading from netapp... need more swag! Jackets, mugs, blankets, shoulder bags, multitools, sunglasses, etc.? I've got the shirts, the swiss army knife, the baseball cap and a few other trinkets already. ;-) ]
They gave you a knife?? I thought that was just for employees! We actually had some input as to which swiss army knife to pick; we had two choices as I recall and I vigorously supported the one with the Phillips screwdriver head. Figured it would come in more handy when fiddling with computer hardware.
I used to collect all the shirts, but there got to me too many. They must have well over 50 in the history of the company.
Bruce
They gave you a knife?? I thought that was just for employees! We actually had some input as to which swiss army knife to pick; we had two choices as I recall and I vigorously supported the one with the Phillips screwdriver head. Figured it would come in more handy when fiddling with computer hardware.
We got 1 swiss army knife with each f540 we purchased. I seem to recall Dan W saying something about it being nifty to have since the filers, even though they had thumbscrews, still required a screwdriver to release (they came tight).
These did not last long; we had several broken blades (lord knows how). This was back in 1996 :)
But the latest batch, in nylon protectors, is *quite* nice.
Good and handy gift.
What would be nice is to be able to purchase some of the more popular shirts (like the green tshirt with Godzilla stomping around on other filer vendors). Free would be good, but it seems like some stuff like this does not make it far out of Sunnyvale :)
Alex
At 05:49 PM 12/30/99 -0500, Alexei Rodriguez wrote:
They gave you a knife?? I thought that was just for employees! We actually had some input as to which swiss army knife to pick; we had two choices as I recall and I vigorously supported the one with the Phillips screwdriver head. Figured it would come in more handy when fiddling with computer hardware.
We got 1 swiss army knife with each f540 we purchased. I seem to recall Dan W saying something about it being nifty to have since the filers, even though they had thumbscrews, still required a screwdriver to release (they came tight).
That's correct... to loosen the thumbscrews and to remove / reseat the mounting screw on the PCI cards.
Happy New Year everybody, and thanks for making 1999 a wonderful year for Network Appliance!
Dan
On Wed, 29 Dec 1999, E Hunter wrote:
Can anyone fill me in on the use of this _wac_ command , what it does, how often it needs to be done, and whehter or not the filer requires downtime to do it?
It is wack, from WAFL Check, a play on UNIX's fsck. Actually it is a collection of filesystem check commands beginning with wack and ending with a letter (z and y come to mind). If you have no hardware bizarre hardware failures or do not encounter some exotic bug you shouldn't have to do it at all. I really remember doing this only once on one filer (we have about 20) and it was due to FC-AL flakiness which was later rectified. I believe that running all incantations of this command requires downtime. Recently NetApp solicited some input as to whether they should engineer another wack command that would minimize downtime and provide a means to profilactically verify filesystem integrity.
Sincerely; Tom
Greetings.
I'm brand-spankin' new to this list, so please please please excuse me if I landed this question in the wrong space/time.
It's an appropriate question for the list.
I'm looking for infomation on NetApps because the company I'm working for is considering a 760 for our network.
Cool. It's a nice box. I like it.
I have been told by someone who is only vaguely familiar with the NetApps that the filesystem has to be maintained in some way by running a _wac_ command,
There are commands, like "wack", that are available to be run in certain modes. They are not part of regular maintenance. They are used if the system has suffered some horrible calamity, like a double disk failure, or single failure combined with extrordinarily stupid user behavior, such as removing a disk and destroying it while the system is rebuilding another failed disk. The circumstances under which these commands need to be run are rare, and under all circumstances, not normal.
but I have been unable to find any information on such a command in a week of searching . Can anyone fill me in on the use of this _wac_ command , what it does, how often it needs to be done, and whehter or not the filer requires downtime to do it?
On most systems, it never needs to be done. If it does need to be done, the system would be offline. It make take a great deal of time for the command to complete. I have had to do this, myself, maybe 3 times in my 5 years of working with NetApps, and those were a long time ago and during times when the filers were working under, uh, strenuous circumstances.
Short answer: Don't worry about it.
On Wed, 29 Dec 1999, E Hunter wrote:
Can anyone fill me in on the use of this _wac_ command , what it does, how often it needs to be done, and whehter or not the filer requires downtime to do it?
I'll chime in here too... our first Netapp (an F220) went into production about April 1997 and we're up to a dozen production filers now. I vaguely remember diddling with `wacky' a long time ago, but it was more out of curiousity (playing on a test filer) than anything else. I've purposely removed drives, powered down shelves, unplugged FC-AL cables, flipped the filer's power on and off rapidly, etc. and never had to run wack, much less lose a filesystem.
1999-12-29-20:34:36 E Hunter:
I'm looking for infomation on NetApps because the company I'm working for is considering a 760 for our network.
Congratulations! Netapps aren't the cheapest disk available, but they may just be the nicest.
I have been told by someone who is only vaguely familiar with the NetApps that the filesystem has to be maintained in some way by running a _wac_ command, but I have been unable to find any information on such a command in a week of searching. Can anyone fill me in on the use of this _wac_ command, what it does, how often it needs to be done, and whehter or not the filer requires downtime to do it?
Lurking on a list like this could give you the impression that this is a routine maintenance chore, but it ain't:-).
When you get at something like the toasters list, you are seeing a tight population of a lot of the heaviest users of netapps, and they only tend to post things when stuff blows up. And if you follow the analysis to its end, it's surprising how often the final answer ends up being "boy, I shouldn't have done that, next time I'll RTFM first".
I've only worked in two companies that used Netapps, and that only for maybe two years altogether, but I ended up working with about a half-dozen of the gizmos over time, and they were invariably plug-'em-in and they go, then you get to forget them.
The trickiest maintenance chore isn't intrinsic to Netapps as such, but rather comes with the territory whenever you start pushing up near a terabyte of data; big horking disk farms exceed the capacity of any available tape media. So backups are no longer a no-brainer. Brains required. Netapp does everything to make it as easy as possible. I'd say WAFL's snapshots are the biggest reason for not considering anything _other_ than a netapp for storing terabytes. For a lot of purposes, my favourite backup strategy is to (a) have a cold spare netapp in the rack (one such cold spare is plenty for many hot toasters), (b) make sure you have a couple of times as much disk space total as you need, so you can collect plenty of snapshots, and (c) occasionally spin a stack of DLTs to back up a candidate snapshot, however often you need archival coverage. For offsite coverage I'd still go with online replication if I could; I've replicated a _lot_ of data with rsync-over-ssh, if you're not in a hurry it just keeps on slogging. You do have to carve the job up into subdirs and sync 'em separately, since rsync builds some O(nfiles) data structures. I would use snapshots for "oops, I wish I hadn't deleted that" coverage, I'd trust the toaster's raid to protect against disk loss, leaving only archival tapes that have to be spun. And DLT juke boxes that can handle 22 tapes aren't that expensive, heavy, or bulky. I recently set up an ADIC FastStor 22 URL:http://www.adic.com/ and it's quite nice. That's somewhere around 1.5TB worth without you having to get up and change tapes. As long as you aren't in a hurry (_love_ them snapshots!) you don't have to work too hard.
-Bennett
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